Shot shells comprise an anterior mouth end and a posterior head end with a powder charge positioned at the head end. A wad is typically positioned over the powder charge toward the mouth end of the cartridge with the payload being contained in the wad. Shot shells are designed to have maximum effectiveness within a designated range. This range is a function of the velocity as well as the size of the shot payload. While effective for many types of hunting, this is a handicap with certain types of small game that might appear at short or long ranges, in which situation the hunter would be unable to change the size of the shot to compensate for the distance at which the game is found.
Many attempts have been made to overcome the limitations of range within a single shot shell. For example, Woodhouse, in U.S. Pat. No. 1,277,810, suggested incorporating two sizes of shot in a single cartridge, in which smaller shot was positioned circumferentially around a core of larger shot. Unfortunately, this arrangement destroys the effectiveness of the charge of small shot, in that the central larger diameter shot would, shortly after exiting the muzzle of the shotgun, disturb the pattern of the circumferential small shot. Similarly, a substantially homogeneous mixture of small and large shot would result in the degradation of the pattern performance of the shot, especially at long ranges.